The Magellanic Bridge cluster NGC 796: Deep optical AO imaging reveals the stellar content and initial mass function of a massive open cluster

NGC 796 is a massive young cluster located 59 kpc from us in the diffuse intergalactic medium of the 1/5-1/10 $Z_{\odot}$ Magellanic Bridge, allowing to probe variations in star formation and stellar evolution processes as a function of metallicity in a resolved fashion, providing a link between resolved studies of nearby solar-metallicity and unresolved distant metal-poor clusters located in high-redshift galaxies. In this paper, we present adaptive optics $gri$H$\alpha$ imaging of NGC 796 (at 0.5", which is ~0.14 pc at the cluster distance) along with optical spectroscopy of two bright members to quantify the cluster properties. Our aim is to explore if star formation and stellar evolution varies as a function of metallicity by comparing the properties of NGC 796 to higher metallicity clusters. We find from isochronal fitting of the cluster main sequence in the colour-magnitude diagram an age of 20$^{+12}_{-5}$ Myr. Based on the cluster luminosity function, we derive a top-heavy stellar initial mass function (IMF) with a slope $\alpha$ = 1.99$\pm$0.2, hinting at an metallicity and/or environmental dependence of the IMF which may lead to a top-heavy IMF in the early Universe. Study of the H$\alpha$ emission line stars reveals that Classical Be stars constitute a higher fraction of the total B-type stars when compared with similar clusters at greater metallicity, providing some support to the chemically homogeneous theory of stellar evolution. Overall, NGC 796 has a total estimated mass of 990$\pm200$ $M_{\odot}$, and a core radius of 1.4$\pm$0.3 pc which classifies it as a massive young open cluster, unique in the diffuse interstellar medium of the Magellanic Bridge.Comment: Accepted for publication in the Astrophysical Journal. Contains 14 pages, 11 figures, and 3 table

Relaxation oscillations, pulses, and travelling waves in the diffusive Volterra delay-differential equation

The diffusive Volterra equation with discrete or continuous delay is studied in the limit of long delays using matched asymptotic expansions. In the case of continuous delay, the procedure was explicitly carried out for general normalized kernels of the form Sigma/sub n=p//sup N/ g/sub n/(t/sup n//T/sup n+1/)e/sup -t/T/, pges2, in the limit in which the strength of the delayed regulation is much greater than that of the instantaneous one, and also for g/sub n/=delta/sub n2/ and any strength ratio. Solutions include homogeneous relaxation oscillations and travelling waves such as pulses, periodic wavetrains, pacemakers and leading centers, so that the diffusive Volterra equation presents the main features of excitable media

Gait parameter differences between the legs during race walking

Prior research on the effects of fatigue during race walking has shown changes in step length and frequency (Knicker & Loch, 1990: New Studies in Athletics, 5, 25–38). It is unclear whether these changes are consistent for both legs. The purpose of the study was to investigate the differences between the legs for kinetic variables during race walking, and to measure changes occurring because of fatigue. The study was approved by the university’s ethics committee and informed consent was given by fourteen international race walkers, of whom four were females (age mean 28.2, s=7.4 years; stature 1.77, s=0.10 m; mass 66.0, s=11.7 kg). Each participant walked for 10 km on a treadmill (Gaitway, Traunstein). The average treadmill speed was 12.4 km h-1 (s=0.7) and each athlete walked at a constant pace. Data were recorded using the Gaitway treadmill, which has two in-dwelling force plates (Kistler, Winterthur). The sampling rate was 1000 Hz. Data were collected for 30 s at four times during the walk, at 2500 m, 4500 m, 6500 m and 8500 m. Statistical analysis consisted of repeated measures ANOVA. There was a significant difference between the legs for first peak force (F1,13=32.6, P¼0.001, Z2=0.71, power=0.99), weight acceptance rate (F1,13=14.5, P=.002, Z2=0.53, power=0.94), and push-off rate (F1,13=36.2, P=0.001, Z2=0.74, power=1), although these differences did not change significantly with distance walked. There was also a significant difference between the legs’ step lengths (F1,13=30.1, P=0.001, Z2=0.70, power=0.99), midsupport forces (F1,13=9.6, P=0.009, Z2=0.42, power=0.82), and propulsive force peaks (F1,13=20.6, P=0.001, Z2=0.61, power=0.99); the overall values for these variables also increased significantly with distance walked (P<0.001, P=0.009, and P<0.001 respectively). However, there was no effect of distance on the differences between the legs for any variable. The results show significant leg dominance during race walking. Athletes should be aware that these imbalances need rectification to prevent injury and maintain efficient walking technique. The imbalances did not appear to worsen with the onset of fatigue although this may occur over the longer championship distances of 20 and 50 km

Case Notes

A look at the decisions in Langevin v. Chenango Court, Inc., 447 F.2d 296 (2d Cir. 1971); Vasquez v. Superior Court of San Joaquin County. 4 Cal. 3d 800, 484 P.2d 964, 94 Cal. Rptr. 796 (1971); and Dickens v. Ernesto, 30 N.Y.2d 61, 281 N.E.2d 153, 330 N.Y.S.2d 346, appeal dismissed, 40 U.S.L.W. 3596 (1972)

inSCALE Baseline Cross-Sectional Survey Uganda

A data collection containing information on 6,501 children under 5 years of age in West Uganda. Data was collected during May - August 2011 as part of a baseline survey prior to implementation of the inSCALE c-RCT in the site. Dataset variables cover socioeconomic and demographic characteristics of households, symptoms of the most recent illness episode for the children during the two weeks preceding the survey, care seeking behaviour, treatments received and details of all self-reported out-of-pocket costs associated with care seeking for the episode of illness. Three datasets are made available: [1] The ‘inSCALE_baseline’ master table covers 1 child per row, and [2] a ‘inSCALE_long_baseline’ table with 1 illness condition per row (if child had more than one illness defined, one row is created for each illness) (5057 - only sick children included hence lower total), and [3] 'inSCALE_baseline_extra_cost' table containing additional data on household direct and indirect costs of care seeking collected in the baseline survey

Preventing child pedestrian injuries and deaths arising from vehicle-child accidents in domestic driveways: An action research project

This research was a three-fold investigation into the viability of previous recommendations for vehicle-related child driveway accident safety . Firstly, the groups most at risk of these types of accidents were determined in order that they could be specifically considered when reviewing the practicalities of previous recommendations . Secondly, the feasibility of previous recommendations was systematically examined through both an extensive literature review and key and expert informant interviews . Based on these, the likelihood of implementation of previous safety recommendations for the identified high risk groups was ascertained, providing a basis on which to abandon some previous recommendations, remove obstacles to others which would enhance practicability and generate further recommendations that would be tenable for the at-risk groups in particular. The key findings of this research were, foremost, that there is a noticeable lack of specific reference to vehicle-related child driveway accidents in any legislation or safety guidelines, as well as a shortage of official data that deal expressly with this type of accident. Further, it was found that the major obstacles to the implementation of previous recommendations - particularly the environmental ones - were cost, autonomy, and spatial constraints. While several recommendations were abandoned due to factors such as unproven or dubious effectiveness and/or prohibitive cost, it was found that the most viable recommendations were characterised by their relatively low cost for the families involved. These recommendations were typically environmental or educational in nature. Thus, the recommendations in this report include some moderate regulatory changes to facilitate greater uptake of environmental and behaviour-modifying recommendations as well as practical ideas that all need to be part of a cohesive campaign to address the issue of vehicle-related child driveway accidents in New Zealand